All the more known mafia-type organizations (cosa nostra, Camorra, n'drangheta) are from Southern Italy. Why isn't there a bigger presence in whole of Italy? Is it a wealth disparity issue? Were other northern organizations suppressed more effectively? Or there are organizations but we dont know much about them?
There is always more to say, but, at root, the problem you're concerned with was initially a product of the exploitative way these regions were run, generally by agents working for absentee landlords, in the eighteenth and nineteenth centuries. I covered these issues in an earlier post which you might like to review while you wait for fresh responses to your question:
How, and when, did the Mafia begin to form in Southern Italy?